RESUMO
The edible fungus Tremella fuciformis was shown to have a high molecular weight (1.87 × 103 kDa) bioactive polysaccharide, denoted as TFP-F1. Monosaccharide composition and NMR analysis of the polysaccharide and its derivatives indicated it contained fucose (Fucp), xylose (Xylp), mannose (Manp), and glucuronic acid (GlcAp) in a ratio of 0.9:1.0:3.2:1.2. Using IR, NMR, and GC-MS spectroscopic data, the structure of TFP-F1 was elucidated as {â3)-[ß-D-GlcAp-(1â2)]-α-D-Manp-(1â3)-α-D-Manp-(1â3)-[α-L-Fucp-(1â2)-ß-D-Xylp-(1â2)]-α-D-Manp-(1â}n, with partial acetylation of C6-OH in mannoses. Furthermore, at a concentration of 1 µg/mL, TFP-F1 was found to stimulate the secretion of TNF-α and IL-6 in J774A.1 macrophage cells in vitro via interaction with toll-like receptor 4 (TLR4). The removal of O-acetyl groups led to the loss of immunomodulatory activities, demonstrating that O-acetyl groups play an essential role in enhancing the production of pro-inflammatory cytokines.
Assuntos
Receptor 4 Toll-Like , Fator de Necrose Tumoral alfa , Acetilação , Basidiomycota , Citocinas , Carboidratos da Dieta , Fucose , Ácido Glucurônico , Imunomodulação , Interleucina-6 , Manose , Monossacarídeos , Polissacarídeos/química , Polissacarídeos/farmacologia , XiloseRESUMO
Klebsiella pneumoniae serotype KN2 is a carbapenem-resistant strain and leads to the health care-associated infections, such as bloodstream infections. Its capsular polysaccharide (CPS) was isolated and cleaved by a specific enzyme from a bacteriophage into a hexasaccharide-repeating unit. With GC-MS, NMR, and Mass analyses, the structure of KN2 CPS was determined to be {â3)-ß-D-Glcp-(1â3)-[α-D-GlcpA-(1â4)-ß-D-Glcp-(1â6)]-α-D-Galp-(1â6)-ß-D-Galp-(1â3)-ß-D-Galp-(1â}n. We demonstrated that 1 µg/mL CPS could stimulate J774A.1 murine macrophages to release tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in vitro. Also, we proved that KN2 CPS induced the immune response through Toll-like receptor 4 (TLR4) in the human embryonic kidney (HEK)-293 cells. Strikingly, the hexasaccharide alone shows the same immune response as the CPS, suggesting that the hexasaccharide can shape the adaptive immunity to be a potential vaccine adjuvant. The glucuronic acid (GlcA) on other polysaccharides can affect the immune response, but the GlcA-reduced KN2 CPS and hexasaccharide still maintain their immunomodulatory activities.